ao-mud/spells/cantrips/ask_yn

#!/bin/sh

question=$1
default_answer=$(echo $2 | tr a-z A-Z)

# Capitalize the default answer and construct the prompt
if [ "$default_answer" = "Y" ]; then
    prompt="${question} (Y/n)? "
else
    prompt="${question} (y/N)? "
fi

# Handle Ctrl-C
trap "printf '\n'; exit 2" 2

# Use stty to make read command work for single character input
old_stty_cfg=$(stty -g)
stty raw -echo
printf "%s" "$prompt" >&2
answer=$( while ! head -c 1 | grep -i '[yn]'; do true; done )
stty "$old_stty_cfg" >&2

# If no answer is given, use the default answer
if [ -z "$answer" ]; then
    answer=$default_answer
fi

# Print the answer and return appropriate exit code
printf "%s\n" "$(echo $answer | tr a-z A-Z)" >&2
sleep 0.01 # Without this, answer gets overwritten by next echo
if [ "$answer" = "Y" -o "$answer" = "y" ]; then
    exit 0
else
    exit 1
fi